Wells are generally drilled into subsurface rocks to access fluids, such as hydrocarbons, stored in subterranean formations. The formations penetrated by a well can be evaluated for various purposes, including for identifying hydrocarbon reservoirs within the formations. During drilling operations, one or more drilling tools in a drill string may be used to test or sample the formations. Following removal of the drill string, a wireline tool may also be run into the well to test or sample the formations. These drilling tools and wireline tools, as well as other wellbore tools conveyed on coiled tubing, slickline, drill pipe, casing, or other means of conveyance, are also referred to herein as “downhole tools.” A downhole tool may be employed alone or in combination with other downhole tools in a downhole tool string.
The measurements taken by downhole tools may be used, for example, to determine downhole conditions or to identify characteristics of formations surrounding boreholes in which the downhole tools are deployed. Some downhole tools include sensors for measuring downhole parameters, such as temperature, pressure, viscosity, resistivity, and the like. Downhole tools can also include various imaging devices, such as micro-resistivity imagers, for generating images that visually represent formation geology. The measurements acquired via such downhole tools may be useful in assessing downhole conditions, understanding formation characteristics, and directing oilfield operations.